1. Field of the Inventions
The present inventions relate to a watercraft having marine propulsion units such as outboard motors and stem drives. More specifically, these inventions relate to an arrangement for a power control device for marine vehicles.
2. Description of the Related Art
When operators run a watercraft having a marine propulsion unit such as outboard motors and stem drives (hereafter inclusively referred to as “outboard motor”), they adjust the opening degree of a throttle valve disposed in the engine intake system to control the power output of the engine. This allows the operator to control the speed, acceleration, and deceleration of the watercraft.
The throttle valve opening typically is adjusted by a main control lever that is provided on the watercraft body and operated by a watercraft operator. As the main control lever is operated, the throttle valve is opened or closed via a mechanical push-pull wire. Where an electronic throttle control is used, a motor for the throttle valve is driven via an electric cable or a wireless system.
The main control lever also can also serve as a gear shift lever. For instance, when the main control lever is tilted forwardly by the operator, the watercraft runs forwardly. When it is tilted rearwardly, the watercraft runs in reverse. When it is at the center position, the transmission is in neutral. Further, the throttle valve moves between the opened and closed positions in response to the forward and rearward tilt angle of the main control lever.
While adjusting the throttle by the main control lever, the operator might also need to steer the watercraft by turning the steering wheel. Since the main control lever is typically provided at the side of the operator's seat, the operator must remove one hand from the steering wheel, and reach out substantially for adjusting the throttle valve opening. In the choppy water or under the high wind, such operation becomes more difficult because the operators must adjust the throttle valve opening frequently. Additionally, the operator may need to turn the rudder against the beam sea and the beam wind, taking into account the timing of swells and the side drift of the watercraft due to the high wind while simultaneously adjusting the throttle position with the main lever.
Japanese Patent Publication JP-A-2004-68704 describes an outboard motor in which the throttle valve opening can be adjusted without the need for multiple steps of control. The outboard motor has an electric air valve that increases or decreases the intake air amount into the engine via a system that is independent of the throttle valve. A control section including an actuator for controlling the opening of the electric air control valve. An engine speed adjusting section is provided on the watercraft body by which the operator can directly input the signals to the control section mentioned above for increasing or decreasing the intake air amount. However, the outboard motor described in the JP-A-2004-68704 publication has the throttle lever provided on the remote-control box located at the side of operator's seat. Thus the operator must remove one hand substantially away from the steering wheel to adjust the throttle valve opening, as was explained above.
The aforementioned engine speed adjusting section for controlling the opening of air control valve independent of the throttle valve may be provided on the steering wheel. However, the amount of air adjustable by the air control valve is smaller than the amount of intake air into the engine through the throttle valve. This is used for the fine tuning of the throttle valve opening. Therefore, operation by the throttle lever is still required when the engine speed has to be changed to a larger extent. The operation can be all the more complicated when the throttle lever is operated in conjunction with the engine speed adjusting section provided on the steering wheel for fine-tuning.